Helmet retaining strap for a mouth guard



FIG. 1 is a perspective view of a helmet retaining strap for a mouth guard showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a side elevation view thereof.

All surfaces not shown form no part of the claimed design. 

CLAIM The ornamental design for a helmet retaining strap for a mouth guard, as shown and described. 